Abstract: The National Academy of Sciences (NAS) Institute of Medicine released a comprehensive report 6 years ago on strategies to reduce underage drinking in this country. The report responded to a congressional request for a review of a broad range of federal, state, and nongovernmental programs, including environmental interventions and programs focused on youth and parent attitudes and behaviors, and for the development of effective strategies to reduce and prevent underage drinking. The resulting recommended policies are embodied in the current set of 16 laws that have been adopted by many states to control underage drinking and impaired driving. No state, however, has enacted all 16 laws (e.g., Utah has enacted 15 of the minimum legal drinking age 21 (MLDA-21) laws, whereas Kentucky has enacted only 7). Moreover, many states that have these laws provide for important exceptions to them. The NAS report has substantial potential to influence state statutes on MLDA and their enforcement. The NAS report is also significant because it points to the need for improved enforcement. Yet, the specific provisions of these laws in some states actually restrict their enforcement. Thus, there is a need to determine the effectiveness of the 16 laws relating to underage drinking and impaired driving and to determine whether adopting and/or strengthening these laws in the states will increase their overall effectiveness. Using the Alcohol Policy Information System and other sources, this application requests funds to build on previous research to document the MLDA laws to support studies of their effectiveness and to evaluate two of the expanded laws (use of a fake identification and social host liability). The specific aims are to (1) document effective dates of 10 MLDA-21 statutes to enable researchers to study the effectiveness of these additional laws in reducing underage drinking and the various consequences of underage drinking; and (2) determine the effects of the fake identification and social host liability laws on underage drinking drivers in fatal crashes using structural equation modeling methods to account more precisely for the differential effects of laws on simultaneous joint outcomes. The fake identification and social host liability laws' annual presence/absence will be cross-tabulated against the presence/absence of the other general safety laws to ensure that there is not a collinearity problem among these binary predictors. PUBLIC HEALTH RELEVANCE: Public Health Relevance: Although most studies demonstrating the effectiveness of the MLDA laws have focused primarily on the two core laws, purchase and possession, the other 14 legislative enhancements have received little study. This limitation in the state of knowledge has recently been highlighted by the national Choose Responsibility campaign (www.chooseresponsibility.org) directed at repealing the federal legislation that resulted in all states setting the MLDA at 21. Using the Alcohol Policy Information System and other sources, this application requests funds to increase and improve the documentation of 10 MLDA laws to support studies of their effectiveness and to evaluate two of the expanded laws (use of a fake identification and social host liability).